This invention relates generally to valve operating mechanisms for use in internal combustion engines and, more particularly, to an oscillating rocker arm assembly and subassembly having rolling members.
Typically, a rocker arm assembly with rolling members is supported on a support shaft mounted perpendicularly on a support stud extending from the head of the engine. The rocker arm is pivoted on the support shaft, which serves as an inner raceway, by means of drawn cup needle roller bearings mounted on the rocker arm. Alternatively, a bearing sleeve may be mounted on the support shaft to provide the inner raceway, permitting use of a non-cylindrical support arm and facilitating the use of powder metal forming.
When bearing sleeves are used in such rocker arm assemblies to provide the inner raceway, fatigue, spalling, wear or other damage to the bearing sleeves may limit the useful life of the rocker arm assemblies. Such damage is exacerbated by the directional loading on the lower portion of the bearing sleeve, that is, that portion of the bearing sleeve nearest the engine head. Accordingly, there is a need to provide a rocker arm assembly that reduces such damage to the bearing sleeves and thereby extends the useful life of the rocker arm assembly.
The foregoing illustrates limitations known to exist in present rocker arm bearing assemblies. Thus, it is apparent that it would be advantageous to provide an alternative directed to overcoming one or more of the limitations set forth above. Accordingly, a suitable alternative is provided including features more fully disclosed hereinafter.